1. Field of the Invention
The disclosed embodiments of the present invention relate to frequency detection, and more particularly, to a frequency detection apparatus with an internal output voltage which changes along with an input signal frequency of an input signal.
2. Description of the Prior Art
Power consumption in the normal operation mode and the standby mode of electronic devices needs to be taken care since the low power requirement is highly demanded in today's communication systems. Particularly, power management designs of portable devices now face new challenges regarding aspects of core and I/O voltages, power management, battery life, etc. A buck converter with synchronous rectification, which is widely applied in portable devices, provides a power saving mode to maintain high efficiency over the entire load range. The converter operates in a pulse frequency modulation (PFM) mode in a light load case, and switches to a pulse width modulation (PWM) mode automatically in a medium or heavy load case. The conventional architecture may need to detect voltage loads of components other than core components, for instance, I/O components; therefore, it consumes more power and has a larger die size. Hence, how to switch between PFM and PWM more efficiently has become an important issue in this field.